How We Grow Our Shellfish

PHASE 1

Hatchery Shellfish hatcheries are located on shore, near a body of water suitable for the cultivation of infant bivalves like hard clams, oysters and bay scallops. Shellfish spawning begins in February to produce juveniles for the summer growing season. Shellfish production from hatcheries insures farmers that there will be a sustainable crop of shellfish each year.

Culture system for micro algae (photo credit – Justin Adams)

Algae production

Marine micro-algae are single celled plants grown for conditioning shellfish broodstock to spawn and feeding shellfish larvae and small seed.

Larvae and Post-set production Shellfish are free swimming larvae for the first two weeks of their life. They are grown in special tanks called conicals

Oyster set trays and downwellers for post-set

Once they are ready to set they are removed from the conicals and put in setting tanks. Set shellfish are called spat, post-set or seed.

PHASE 2

Shellfish Nursery Once the shellfish are too large to feed cultured micro algae, they are moved to a nursery system. A nursery system is usually located on, or floating off of a dock. Shellfish are kept in containers called upwellers. Natural bay water flows through the containers providing food.

Land-based upweller for small seed (photo courtesy Gregg Rivara)

Small oyster seed

Culling machine used to screen shellfish seed

Floating upwelling system

The nursery system is quite labor intensive. The seed shellfish are grown in the nursery from April until October.

They must be screened each week to separate the fast growing seed from the slower growing seed. Seed ready to plant is removed during the screening process.

PHASE 3

Grow-out When shellfish seed are large enough they are placed in cages or free planted on farmed bottom. The cage grown shellfish (oysters and bay scallops) are tended regularly. When the shellfish are large enough they are harvested from the cages.

Tending oyster cages

Bay scallops from grow out cages

Bottom cultivation work boat

Hard clam harvester

Shellfish aquaculture is farming that requires access to the shore and underwater land. Each farm is unique to the area available for cultivation. A great deal of time, effort and capital is required to produce animals for harvest.

Oysters and hard clams can be planted directly on the bottom. Hard clams will burrow into the bay bottom. They are not disturbed until harvest time.